Mo Single-Atom Nanozyme Anchored to the 2D N‑Doped Carbon Film: Catalytic Mechanism, Visual Monitoring of Choline, and Evaluation of Intracellular ROS Generation

• Published in: ACS applied materials & interfaces Vol. 15; no. 30; pp. 36124 - 36134
• Main Authors: Sun, Qijun, Xu, Xiaoyu, Liu, Song, Wu, Xinzhao, Yin, Chenhui, Wu, Meng, Chen, Yuxue, Niu, Na, Chen, Ligang, Bai, Fuquan
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 02.08.2023
• Subjects: blood serum; Carbon; Catalysis; Choline; choline oxidase; density functional theory; detection limit; Energy, Environmental, and Catalysis Applications; Humans; Hydrogen Peroxide; mobile telephones; neoplasms; pyrolysis; Reactive Oxygen Species; toxicity; Mo single-atom nanozyme; peroxidase-like mimetic; intratumoral •OH generation; visual sensing of choline; density functional theory
• DOI: 10.1021/acsami.3c04761
• ISSN: 1944-8244; 1944-8252

Single-atom nanozymes (SANs) have attracted great attention in constructing devices for instant biosensing due to their excellent stability and atom utilization. Here, Mo atoms were immobilized in 2D nitrogen-doped carbon films by cascade-anchored one-pot pyrolysis to obtain Mo single-atom nanozyme (Mo-SAN) with high atomic loading (4.79 wt %) and peroxidase-like activity. The coordination environment and enzyme-like activity mechanism of Mo-SAN were studied by combining synchrotron radiation and density functional theory. The strong oxophilicity of single-atom Mo makes the catalytic center more capable of transferring electrons to free radicals to selectively generate •OH in the presence of H2O2. Choline oxidase and Mo-SAN were used as signal opening unit and signal amplification unit, respectively. Combining the portability and visualization functions of smartphone and test strips, a paper-based visual sensing platform was constructed, which can accurately identify choline at a concentration of 0.5–35 μM with a limit of detection as low as 0.12 μM. The recovery of human serum samples was 96.4–102.2%, with an error of less than 5%. Furthermore, the potential of Mo-SAN to efficiently generate toxic •OH in tumor cells was intuitively confirmed. This work provides a technical and theoretical basis for designing highly active SANs and detecting neurological markers.